Free Astronomy Magazine May-June 2020

50 MAY-JUNE 2020 5142, astronomers could pinpoint where phos- phorus-bearing molecules, like phosphorus monoxide, form. New stars and planetary sys- tems arise in cloud-like regions of gas and dust in between stars, making these interstellar clouds the ideal places to start the search for life’s building blocks. The ALMA observations showed that phospho- rus-bearing molecules are created as massive stars are formed. Flows of gas from young mas- sive stars open up cavities in interstellar clouds. Molecules containing phosphorus form on the cavity walls, through the combined action of shocks and radiation from the infant star. The astronomers have also shown that phosphorus monoxide is the most abundant phosphorus- bearing molecule in the cavity walls. After searching for this molecule in star-form- ing regions with ALMA, the European team moved on to a Solar System object: the now- ALMA and Rosetta map the journey of phosphorus P hosphorus, present in our DNA and cell membranes, is an essential element for life as we know it. But how it arrived on the early Earth is something of a mystery. As- tronomers have now traced the journey of phosphorus from star-forming regions to comets using the combined powers of ALMA and the European Space Agency’s probe Rosetta. Their research shows, for the first time, where molecules containing phosphorus form, how this element is carried in comets, and how a particular molecule may have played a crucial role in starting life on our planet. “Life appeared on Earth about 4 billion years ago, but we still do not know the processes that made it possible,” says Víctor Rivilla, the lead author of a new study published today in the journal Monthly Notices of the Royal As- tronomical Society . The new results from the Atacama Large Millimeter/Submillimeter Array (ALMA), in which the European Southern Ob- servatory (ESO) is a partner, and from the ROSINA instrument on board Rosetta, show that phosphorus monoxide is a key piece in the origin-of-life puzzle. With the power of ALMA, which allowed a de- tailed look into the star-forming region AFGL by ESO T his infographic shows the key results from a study that has revealed the interstellar thread of phosphorus, one of life’s building blocks. [ALMA (ESO/NAOJ/NRAO), Rivilla et al.; ESO/L. Calçada; ESA/Rosetta/NAVCAM; Mario Weigand, www.SkyTrip.de ]